On February 8, the Financial Times website published an article entitled "What the changing red line of the West means for Ukraine", written by Felicia Schwartz and Ben Hall. The full text is summarized as follows: Kiev's allies have repeatedly crossed their red line on the issue of arms supply. However, on the occasion of the first anniversary of the outbreak of the Russian-Uzbekistan conflict, the concerns of the United States and Europe about the escalation of the conflict in Russia have not changed substantially, and still affect the following decisions, including the decision on whether to provide fighter aircraft. The United States and its partners have promised to provide many systems that were once considered to be prohibited, including the latest tanks, as well as the "Seahorse" rocket system, the "Patriot" missile defense system, and so on. Some western officials and analysts said that the allies have constantly broken through the limits set by themselves, which reflects Ukraine's changing battlefield needs, rather than the allies' assessment of the threat escalation. Some analysts said that it is purposeful for Washington to constantly redefine which weapons systems will aggravate the conflict. Ukrainian officials and their hawkish allies in Eastern Europe said that Russia's threat - including the explicit mention of the use of nuclear weapons - was a tactic of intimidation aimed at preventing Kiev's allies from providing advanced weapons. But Aleksi Leznikov, the outgoing Ukrainian defense minister, took an unusual move this week, promising not to use weapons provided by the West to attack Russian territory. This is a sign that Ukraine believes that the United States' concern about the escalation of the conflict has seriously hindered the supply of long-range weapons. Last September, after the collapse of Russia's defense line in Kharkov, people's concern about the escalation of the conflict reached its peak. Russian President Vladimir Putin ordered the mobilization of 300000 people and warned the West that Russia might use nuclear weapons. He said: "If its territorial integrity is threatened, Russia will use all available means." Since then, Russia has lowered its threat tone. Putin seemed to hint again last week that nuclear weapons might be used. In response to the commitment of Germany and other countries to provide western tanks to Ukraine, he said, "We have a way to respond, and our response will not be limited to the use of armored vehicles". Some experts said that the nuclear threat of the Kremlin was intended to inspire the Russians and mobilize them to join the war. During the period when Russia made fierce remarks last year, American officials did not find any threatening changes in Russia's nuclear posture. However, they will still take this risk seriously and constantly monitor any sign that Russia may launch nuclear weapons. A report released by RAND last month said that there was still reason to believe that Russia might use nuclear weapons, especially because Putin believed that the war was "almost life-and-death". (Outlook New Era)