Biden's decision came last week, the officials said, after a series of high-level meetings and an internal debate over how to meet Ukraine's pressing needs for bolstered air defences without jeopardizing US combat readiness. This comes as Kyiv is struggling to fend off Russian attacks on its cities, infrastructure and electrical grid

The new Patriot system -- the second that the United States has sent to Ukraine -- will come from Poland, where it has been protecting a rotational force of American troops who will be returning to the US, officials said

According to the officials, the system could be deployed to Ukraine's front lines in the next several days, depending on any maintenance or modifications it needs

Considered one of the United States' best air defence weapons, the Patriot includes a powerful radar system and mobile launchers that fire missiles at incoming projectiles, as reported by the NYT

It is also one of the scarcest weapons systems in the US arsenal. Pentagon officials refuse to disclose how many it has, but one senior military official said that the Army has deployed only 14 of them, in the US and around the world

Notably, Patriots are also held by American allies and two of those nations have sent a couple to Ukraine, but US officials say they hope European powers will send more

Pentagon officials did not want to move any batteries from the US. There is a Patriot battery at Fort Sill, Oklahoma, for training American and Ukrainian troops, but moving it would take away training, the New York Times reported citing officials. Other batteries protecting bases and troops in the US, including in Hawaii, were either deemed too far away or necessary for homeland defence

Defence Secretary Lloyd Austin and other senior Pentagon leaders have appealed to European allies to transfer their systems to Ukraine