The US is said to be sending a second Patriot to Ukraine, where it's played havoc with Russian jets and missiles

• The US has agreed to send a second Patriot system to Ukraine, according to reports.
• Ukraine has been given a handful of the missile systems from its allies, but says it needs more.
• Patriots help stop Russian attacks, but Ukraine's allies are reluctant to reduce their own arsenals.

A second US Patriot system is headed for Ukraine following appeals for further air defenses, according to reports.