WP is white phosphorous, correct?

Yup, anything to distract the missile gunner!

Yes it is. It is used for TWO reasons. First, it visually obscures the tank from the gunner. Second, it is VERY hot, which obscures BOTH Thermal and Active/Passive IR Sights (IR Sights can also be obscured by normal HC smoke as well). The WP ALSO blocks the IR Trackers that virtually ALL SACLOS missile launchers use to give guidance commands to the missile. Once a missile passes through a WP smoke cloud (or a Dual Spectrum* HC smoke cloud, or the Shorta's ATGM Defense System's aerosol mist), the IR Tracker on the CLU (command, launch unit) can no longer see either the missile's IR tail flare OR the target... making flight corrections IMPOSSIBLE for the computer. The missile WILL begin to deviate without those flight corrections.

Laser-Guided Missiles like the Copperhead, HellFire, and Soviet Tank-launched AT missiles ride an IR laser to the target AND these are ALSO BLOCKED by WP, Dual Spectrum* Smoke, and the Shorta aerosol system. The missile will not be able to see the laser beam once it enters the cloud and will "nose-dive" after about 2-3 seconds to prevent "collateral damage" from an "uncontrolled missile."

Ironically, MCLOS Missiles (which are flown to the target by the operator) such as early versions of the Swingfire, the Soviet AT-2 swatter, and the French SS10 & SS11 are much less affected by smoke (because the operator can "guestimate" the target's location) and are completely unaffected by the Shorta's aerosol (because it's transparent to allow Soviet tankers to shoot through it). However, these are only found in the "Third World" by the mid 90's.

*Dual Spectrum smoke is a type of smoke grenade that produces both an IR and visible smoke cloud to obscure a target. It was in common production from about 1995 until this very day.

Marine Antiarmor men are taught to use explosives to simulate backblast
 

USMC antiarmor gunners (who are primarily armed with TOW, Dragon (during T2K era), Javelin (now), and SMAW) are taught to use 1# blocks of TNT on electric firing devices set 30 - 100 m from their position to draw fire, deceive the enemy about the size of the defending force and keep enemy from pinpointing the target. This is most often going to be done when the unit has had time to set in a proper defense. Very often the unit would have two charges rigged to detonate on one command. As a result the enemy "perceives" they have been fired on by 3 missiles rather then just one.

The actual missile is fired by the gunner, the driver or ammo man (depending on how they are moving) fires the charge AFTER the missile is fired.

For a deliberate defense they might lay out several different strings of charges. The last string might be used without any real missiles to cover the withdraw. Smoke pots may also be employed that way.

In the ACRs, mid 1980s, it was doctrine to have the scout section (two M-901s and two M113/Dragon tracks) start the engagement with long range TOW shots before relocating, the Dragon tracks would cover the hammerhead while they moved to alternative positions, as well as engage targets of opportunity.

While this was going on the, tank section would direct mortar and artillery fires while overwatching the scouts. When it came time for the scouts to displace to the next fighting position (usually after 4-6 TOW shots), then the tanks would hand over the calls for fire and engage direct fire for a dozen or so rounds, moving between alternative positions after each shot. Then rinse, lather and repeat as necessary.

The intention was, to convince the Soviet leading elements that they had stumbled into a mechanical task force and force them to deploy for hasty attack, while we continued to engage with artillery, missiles and main gun and leading them into minefields, obstacles, and maybe a battalion task force or two.