<b>Live updates: follow the latest news on </b><a href="https://www.thenationalnews.com/world/2022/02/18/russia-ukraine-latest-news/"><b>Russia-Ukraine</b></a> The US assesses that Poland’s proposal to transfer its fleet of Soviet-designed fighter jets to Ukraine would not result in any “significant effectiveness” for the Ukrainian military against Russia, a US defence official told Congress on Thursday. “We are trying to provide everything we can that really helps them with air defence and we don’t see significant effectiveness tied to those aeroplanes specifically,” Mara Karlin, the assistant secretary of defence for strategy, told the Senate. “We’re really focusing in particular on what we see is them needing most: anti-armour and air defence capabilities. Ukraine’s air force does have several squadrons of mission-capable aircraft in this contested airspace but what we are seeing is that they really need greater air defence.” Ms Karlin also said that the US has not seen Ukraine using its current fleet of fighter jets “to the extent that one might suggest". Still, Ukraine has specifically requested more fighter jets and the Ukrainian military could integrate the 28 MiG-29s that Poland has offered into its current fleet, given its heavy reliance on Soviet-era weapons systems. But the Polish fleet has been upgraded several times, which could potentially require Ukrainian pilots to undergo training on how to use the more advanced aircraft. Poland blindsided Washington with an announcement this week that it would turn over custody of its MiG-29 fleet to the US at a Nato base in Germany. The surprise announcement, made without consulting Washington, happened right as <a href="https://www.thenationalnews.com/world/us-news/2022/03/09/kamala-harris-poland-trip-takes-abrupt-turn/" target="_blank">Vice President Kamala Harris travelled to Warsaw</a>. The US military is unaccustomed to operating Soviet-designed technology and <a href="https://www.thenationalnews.com/world/2022/03/09/why-does-poland-want-to-give-mig-29-jets-to-the-us-and-could-they-help-ukraine/" target="_blank">the Pentagon said that the Polish proposal is “not tenable”. </a> “At this point, we are consulting very closely with Poland and our other Nato allies on the best way forward,” said Jessica Lewis, the assistant secretary of state for political-military affairs, while speaking before the Senate alongside Ms Karlin. And while Secretary of State Antony Blinken said on Sunday that he had given US Nato allies the “green light” to transfer fighter jets to Ukraine, Undersecretary of State for Political Affairs <a href="https://www.thenationalnews.com/world/us-news/2022/03/08/poland-ready-to-hand-its-russian-made-mig-29-jets-to-us/" target="_blank">Victoria Nuland told the Senate on Tuesday that “there are some mixed views among allies and even within the administration” on transferring the Polish fleet</a>. Mr Blinken said on Wednesday that <a href="https://www.thenationalnews.com/world/us-news/2022/03/09/blinken-russia-will-suffer-long-bloody-drawn-out-mess-in-ukraine/" target="_blank">the US would have to “work through” the MiG-29 transfer with Poland and Ukraine</a>. And Ms Karlin on Thursday pushed back against Poland’s expectation that the US should enable any potential transfer rather than providing the aircraft directly to Ukraine itself. “There are a whole lot of logistics that would have to happen should Poland wish to transfer them,” said Ms Karlin. “Should they wish to do so, it is up to them, rather than of course then them going through us.” Still, Republican and Democratic senators alike pushed back against President Joe Biden administration's hesitancy over the MiG-29 issue and told Ms Karlin that they needed more specific information as to why the Pentagon views transferring fighter jets to Ukraine as less effective than land-based air defence systems. Democrat Jeanne Shaheen criticised “bickering among members” of the Biden administration and called on the Pentagon and State Department to provide Congress with a “better answer” as to its stance on the MiG-29 transfer. Republican Mitt Romney said that the Biden administration has not provided any “logic” for “the lack of rapidity in making this decision and getting in the mix” while suggesting a classified briefing to receive more answers would be helpful. Bob Menendez, Democratic chairman of the Senate Foreign Relations Committee, implied that he could use his jurisdiction over arms sales as leverage to procure more answers from the Biden administration on the MiG-29 issue — raising the prospect that he could hold up arms sales to other countries over Ukraine. “There may be a perfectly valid and good reason, I think all of us should know,” said Mr Menendez. “If there is no perfectly valid and good reason, then we need to know that, too.” Correction: A quote by Mara Karlin was misattributed to Jessica Lewis in an earlier version of this story. The attribution has been updated to reflect the appropriate speaker.