A US-provided M142 High Mobility Artillery Rocket System launches a rocket at Russian positions on Dec. 29, 2023 in Ukraine.Photo by Serhii Mykhalchuk/Global Images Ukraine via Getty ImagesThe US has long restricted Ukraine from using American weapons to strike targets inside Russia.Analysts and officials say this policy is interfering with Ukraine's ability to defend itself.But Kyiv is pushing the US to change its stance in the wake of the Russia's new Kharkiv assault.The Biden administration's policy restricting Ukraine from using US-provided weapons to strike military targets inside Russia is hamstringing Kyiv's ability to defend itself, analysts and officials say.The US has sent Ukraine billions of dollars in security assistance over the course of the war, but it has barred the country from using American weaponry, especially certain powerful long-range missiles, to carry out strikes across the border.Washington has been unwavering in its stance on this matter, instead giving Kyiv approval to only hit targets within Russian-occupied territory in Ukraine.But the Biden administration is facing increasing pressure to soften this long-held policy in the wake of a new Russian assault in Ukraine's northeastern Kharkiv region, which began earlier this month.