The UN force in Lebanon under the leadership of a main Middle Eastern player, France, is now nearly at full strength including 2,000 German troops by permission of Israel and Indonesia also by permission from Israel. The force includes Chinese and Russians.
What is the signal? WE (the powers of the UN) are in Lebanon ready to stop Hezbollah from acting after Iran is attacked to destroy its nuclear facilities. WE (as NATO) are on your eastern border in Afganistan.
This is the strongest signal imaginable to Iran. There are only a few more signals that will be given before the Security Council authorizes a coalition of forces to bomb Iranian nuclear sites.
Interestingly, Syria read the message and has now offered to begin negotiations with Israel on a peace treaty. Having UN troops readily at-hand, makes the negotiations possible.